…or at least “fine” them for calling. While it might inconvenience some callers you might want to speak with, having your only phone forward to a 900 number (in your company’s name–“Telemarketers, Welcome!” or some such) that charges $5 or $10 a minute might–just maybe–hold down the number of telemarketing calls you would receive.
And you could always offer your mom a refund.